Gear Whine Noise Reduction by Transmission Error and Contact Pattern Optimization: Simulation and Testing Correlation

During product development testing, a gear whine issue was identified with a gearbox. The noise was present regardless of the load, observed throughout the operating speed range, and it was especially noticeable at certain points of the operating conditions. A high-fidelity simulation model was built to recreate the issue observed in testing and the objective was to find possible ways to reduce the gear whine. The peak-to-peak transmission error (PPTE or TE), which is the main excitation for gear whine, was evaluated, using the simulation model, throughout the operating conditions, and it showed a peak at the same points as observed in testing. This was attributed to the fact that these gears act as both driving and driven components, which causes fluctuating moment on the gear mesh, and thus the load sharing changes continuously, causing variation in excitation throughout the operating load cycle. This excitation is a function of gear geometry and can be reduced by optimizing the geometry. After conducting several optimization iterations using a full factorial and genetic algorithm DOE, a comprehensive study was performed on the effect of tolerances, and microgeometry specifications were developed that reduced the TE for most load conditions. An evaluation of dynamic transmission error (DTE) also showed an improvement. New parts were manufactured using the recommended geometry and tested for noise. Testing showed a significant improvement in gear whine (more than 6dB for most cases) throughout the operating load cycle. This activity helped to develop new predictive simulation workflows to resolve design issues analytically and effectively within a relatively short period of time.